System and method for the measurement of stretch film

ABSTRACT

A system for determining an amount of stretch film unwound from a stretch film dispensing apparatus. The stretch film dispensing apparatus includes a roller, from which the stretch film can be unwound, at least one supply roll sensor positioned relative to the roller to sense a distance from the at least one supply roll sensor to an outside face of a supply roll on a core on the roller, and a controller. The controller is configured to determine the amount of stretch film unwound based on the one or more signals provided by the at least one supply roll sensor.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to U.S. Provisional Patent Application No. 62,656,683, filed Apr. 12, 2018, which is incorporated herein by reference in its entirety.

BACKGROUND

Stretch film is typically a plastic-based film that can be stretched and applied to or wrapped around one or more items. Stretch film is typically fabricated from linear low-density polyethylene (LLDPE). Stretch film can also be manufactured from or include other materials and layers while maintaining an ability to stretch. Once manufactured, stretch film is wound around a cylindrical core to produce a supply roll. Most stretch film can stretch between 50% and 500% of the manufactured length of stretch film originally wound around the core.

Stretch film is commonly applied as a wrap around one or more items in order to tightly bind the item(s). The binding of the item(s) occurs as a result of elastic recovery from the stretch film being stretched at one or more steps of a wrapping cycle. The wrapping cycle can be manual, semi-automated, or automated. The semi-automated and automated processes often include a stretch film machine. These machines typically include a platform or a conveyor on which the item(s) to be wrapped can be placed. A stretch film dispenser then automatically wraps the stretch film around the item(s) on the platform or conveyor. The stretch film dispenser can consist of one or more rollers on which the core of the supply roll of stretch film can be coupled. The supply roll coupled to the roller can be horizontal or at an angle or variable angle as required by the stretch film machine. Some stretch film machines move the roller to which the stretch film is mounted so that the item(s) to be wrapped can maintain position. Other stretch film machines maintain the location of the roller and spin or move the item(s) to be wrapped during the wrapping cycle. Further, a combination of moving or rotating both the roller and the item(s) can be used in a stretch film machine to complete the selected wrapping cycle.

The stretch film machine can also include an additional series of rollers over which the unwound stretch film passes and can be stretched. The additional series of rollers are calibrated to apply a specific force to the stretch film in order to obtain a desired elastic tension and stretch film thickness for the wrapping cycle. Stretch film stretches as soon as it leaves the core which makes determining how much stretch film is unwound from the core challenging. The amount of stretch film unwound from the core is a useful measurement in cost analysis and allows for adjustments to be made to wrap cycle settings. Knowing the amount of stretch film unwound from the core of a supply roll also allows a user to determine the amount of stretch film still wound around the core. The amount of stretch film that remains on the core of a supply roll allows a user to reduce waste and maintain the quality of the wrap. For example, if the supply rolls runs out of stretch film during the wrap cycle, it is likely the wrap cycle will have to start again from the beginning with a new roll of stretch film. Likewise, if the supply roll is near the end of the stretch film, there is often a difference in the quality of the stretch film resulting in an undesirable wrap of the item(s). If a user is informed that the stretch film on the core is too low to adequately complete the selected wrap cycle, the stretch film left on the core can be recycled instead of used for a partial wrap or a wrap of undesired quality. Often, the entire wrap cycle is repeated over or in place of a partial wrap or a wrap of undesired quality. Having to repeatedly run the machine to wrap the same item(s) consumes additional stretch film, energy and time.

It is known to measure the amount of unwound stretch film using a variety of sensors to count the number of rotations of one or more rollers or one or more roller shafts. However, the supply roll or stretch film can slip on the rollers; introducing error to the measurement. It is also known to use weight sensors and rotary sensors that engage the stretch film or the roller to measure the amount of stretch film unwound from the core of the supply roll. However, sensors that require direct contact to obtain a measurement can experience greater wear, are more subject to damage, and are subject to disengagement, introducing errors into measurements. It is also known to use optical or ultrasonic sensors to detect breaks in the stretch wrap, measure dimensions of the load to be wrapped, or measure a distance to an outside surface of a stretch wrap on a supply roll to calculate an amount of time until the supply roll is empty. See, for example, JPH01110467.

BRIEF DESCRIPTION

In one aspect, the present disclosure relates to a system for determining an amount of stretch film unwound from a stretch film dispensing apparatus. The stretch film dispensing apparatus includes a roller, one or more supply roll sensors, and a controller. The stretch film can be rotated about a longitudinal axis and unwound from a core of a supply roll that is placed onto or otherwise coupled to the roller. The one or more supply roll sensors are positioned relative to the roller to measure a distance from the one or more supply roll sensors to an outside face of the wound stretch film on the supply roll. The one or more supply roll sensors are configured to take a first measure of the distance and, after stretch film is unwound from the core of the supply roll, take a second measure of the distance, and send signals representative of the first and second distances to the controller. A core sensor is positioned relative to the roller to measure a core distance from the core sensor to an outside face of the core and send a signal representative of the core distance to the controller. The controller is configured to determine the amount of stretch film unwound based on the one or more signals from the one or more supply roll sensors and the core distance.

Another aspect of the present disclosure relates to a method of measuring an amount of stretch film unwound from a supply roll about a longitudinal axis. The method can begin with measuring one or more distances from one or more points radially away from the supply roll to an outside face of the supply roll. Alternatively or additionally, a second distance can be measured one or more times from one or more points radially away from the supply roll to the outside face of the supply roll after stretch film has been unwound from the supply roll. A third distance can be measured one or more times from one or more points radially away from the supply roll to the outside face of the core. The amount of stretch film unwound from the supply roll can then be determined based on the one or more first and second distances, and a third distance between the longitudinal axis and at least one of the first or second measures.

BRIEF DESCRIPTION OF THE DRAWINGS

In the drawings:

FIG. 1A is a schematic, cross-sectional view of a system for determining an amount of stretch film unwound from a stretch film dispensing apparatus.

FIG. 1B is a schematic, cross-sectional view of a stretch film supply roll.

FIG. 1C is a schematic, cross-sectional view of the stretch film supply roll coupled to the system for determining an amount of stretch film unwound from a stretch film dispensing apparatus.

FIG. 2 is a schematic, top view of the stretch film supply roll coupled the system for determining the amount of stretch film unwound from the stretch film dispensing apparatus of FIG. 1C.

FIG. 3 is a schematic view of a controller of the system for determining the amount of stretch film unwound from the stretch film dispensing apparatus of FIG. 1A, FIG. 1B, FIG. 1C, and FIG. 2.

FIG. 4 is a flow chart showing a method for determining an amount of stretch film unwound from a stretch film dispensing apparatus using the system of FIG. 1A, FIG. 1B, FIG. 1C, FIG. 2, and FIG. 3.

DESCRIPTION

Herein, unless otherwise noted, the term “stretch film” applies to a film having the capability to stretch from an original manufactured length. Stretch film can be manufactured in a variety of ways; non-limiting examples include being cast or blown. The primary material used to manufacture stretch film is typically linear low-density polyethylene (LLDPE); however, the term stretch film is not limited to a LLDPE base and can include multiple layers and varieties of plastics or other materials in combination with or in place of LLDPE. Stretch film has a manufactured thickness; also known as a gauge. Since the thickness of the stretch film changes as the stretch film is stretched, herein, the “thickness of the wound stretch film” will pertain, unless otherwise noted, to the thickness of the stretch film after manufacturing and prior to being stretched.

Herein, unless otherwise noted, the term “core” refers to a shaft on which stretch film can be wound. The core can be constructed from a variety of materials. Non-limiting examples include cardboard, plastic, metal, glass, or paper. The core is often in the shape of a hollow cylindrical shaft, but can, in some circumstances, be formed in different shapes. The core can be a variety of lengths compared to the wound stretch film. The core can protrude from the wound stretch film on one or more sides; it can be the same length as an aspect of the wound stretch film, or it can be shorter than an aspect of the wound stretch film. Once the stretch film is wound around the core, the core can remain in at least partial contact with the wound stretch film or the core can be removed.

Herein, unless otherwise noted, the term “supply roll” will refer to stretch film that is wound around a core.

All directional references (e.g., radial, axial, proximal, distal, upper, lower, upward, downward, left, right, lateral, front, back, top, bottom, above, below, vertical, horizontal, clockwise, counterclockwise, upstream, downstream, forward, aft, etc.) are only used for identification purposes to aid the reader's understanding of the present disclosure, and do not create limitations, particularly as to the position, orientation, or use of aspects of the disclosure described herein. Connection references (e.g., attached, coupled, connected, and joined) are to be construed broadly and can include intermediate members between a collection of elements and relative movement between elements unless otherwise indicated. As such, connection references do not necessarily infer that two elements are directly connected and in fixed relation to one another. The exemplary drawings are for purposes of illustration only and the dimensions, positions, order and relative sizes reflected in the drawings attached hereto can vary.

As illustrated in FIG. 1A, FIG. 1C and FIG. 2, a system 10 includes, at a minimum, a roller 12 mounted to a support structure, at least one supply roll sensor 50, and a controller 80. The system 10 can optionally include a core sensor 24, a rotation sensor 26, and a user interface 28.

While shown vertically in FIG. 1A, FIG. 1B, and FIG. 1C, the roller 12 can be horizontal or at an angle or variable angle as required by the stretch film dispensing apparatus. The roller 12 is illustrated as a solid cylindrical shaft with a longitudinal axis 14 and a roller radius (RR) 16; however, the roller can be any shape or have one or more portions that are hollow. The roller 12 can be mounted to a support structure of a stretch film machine. The support structure can include, but is not limited to; a platform or frame. The support structure of the roller 12 can, in any combination or singularity; rotate, move, or remain stationary relative to the ground before, during, or at the conclusion of a wrapping cycle. Likewise, the roller 12, relative to the support structure, can, in any combination or singularity; rotate, move, or remain stationary before, during, or at the conclusion of a wrapping cycle. Non-limiting examples of the motion of the roller 12 can include one or more of: the rotation of roller 12 driven by a motor, belt, or other external drive force; or the roller 12 can be mounted with bearings and allowed to freely rotate around the longitudinal axis 14 at an angle relative to the support structure.

As illustrated in FIG. 1B, FIG. 1C, and FIG. 2, a supply roll 20 includes a core 30 on which is a supply of wound stretch film 40. The supply roll 20 can be coupled to the roller 12. Non-limiting examples of how the supply roll 20 can be coupled to the roller 12 include: a lock or clasp mechanism to secure the supply roll 20 and the roller 12; a press fit of the roller 12 through the core 30 of the supply roll 20; a loose fit of the roller 12 through the core 30 of the supply roll 20; an adhesive applied between the supply roll 20 and the roller 12; a magnetic force between the supply roll 20 and the roller 12; or a static force between the supply roll 20 and the roller 12.

The core 30 has core edges 31, 32 that define a core inside face 33 and a core outside face 34. The core 30 has a core inner radius (CIR) 36 measured from the longitudinal axis 14 to the core inside face 33. The core 30 also has a core outside radius (COR) 38 measured from the longitudinal axis 14 to the core outside face 34.

The wound stretch film 40 has film edges 41, 42 that define a stretch film inside face 43 and a stretch film outside face 44. The wound stretch film 40 has a stretch film inside radius that can be equal to the core outside radius (COR) 38 measured from the longitudinal axis 14 to the stretch film inside face 43. The wound stretch film 40 also has a stretch film outside radius (SFOR) 47 measured from the longitudinal axis 14 to the stretch film outside face 44. The stretch film outside face 44 is an outside face of the supply roll. A remaining stretch film depth (RSFD) 46 is the distance from stretch film inside face 43 to the stretch film outside face 44. The remaining stretch film depth (RSFD) 46 can also be calculated by subtracting the core outside radius (COR) 38 from the stretch film outside radius (SFOR) 47.

The supply roll 20 can include an information label 22. The information label 22 can be located, but is not limited to, the core inside face 33, the core outside face 34, the stretch film inside face 43, the stretch film outside face 44, or anywhere on the supply roll 20 packaging. Information label 22 can be a barcode, a Quick Response code, a color or numeric indicator, Radio Frequency Identification circuit or chip, a Near Field Communication circuit or chip, one or more magnets, patterned gaps, one or more images, or any other known art of communicating or storing data. Information label 22 can include, but is not limited to, information about the supply roll 20. Non-limiting examples of information about the supply roll 20 include: data regarding a thickness or gauge of the wound stretch film 40; an amount of the wound stretch film 40; a dimension of the core 30; a dimension of the wound stretch film 40 on the core 30; one or more elastic properties of the wound stretch film 40; one or more chemical properties of the wound stretch film 40; or one or more manufacturing properties of the supply roll 20.

The at least one supply roll sensor 50 of the system 10 is positioned relative to the roller 12 to sense a wrap distance (WD) 52 from the at least one supply roll sensor 50 to a stretch film outside face 44. Preferably, as illustrated in FIG. 1C, and FIG. 2, the position of the at least one supply roll sensor 50 can be a first radial distance (1RD) 54 from the longitudinal axis 14 of the supply roll 20 on roller 12, so that the at least one supply roll sensor 50 is not in physical contact with the wound stretch film 40.

When the supply roll 20 is coupled to the roller 12 in the vertical position as illustrated in FIG. 1C, the at least one supply roll sensor 50 is preferably positioned to sense the wrap distance (WD) 52 from the at least one supply roll sensor 50 to a lower portion 48 of the stretch film outside face 44. The lower portion 48 of stretch film outside face 44 can be, but is not limited to, a location that is closer to edge 42 than edge 41. When the wrap distance (WD) 52 is measured from the at least one supply roll sensor 50 to a lower portion 48 of the stretch film outside face 44; supply rolls with a variety of core lengths can be coupled to the roller 12 without having to change the location of the at least one supply roll sensor 50.

The at least one supply roll sensor 50 can communicate with the controller 80. Communication with the controller 80 can be, but is not limited to, electrical signal, optical signal, sonic signal, electromagnetic signal, any other wireless signal processes, induction, or user input of data read from the at least one supply roll sensor 50.

The at least one supply roll sensor 50 can communicate one or more signals representative of the sensed wrap distance (WD) 52 to the controller 80. The controller 80, in turn, can, among other things, analyze the signal(s) to identify possible outliers; determine an average value related to the signal(s); or analyze the signal(s) to determine possible obstructions to one or more of the at least one supply roll sensor 50. Further, while FIG. 1A, FIG. 1C, FIG. 2, and FIG. 3 demonstrate the at least one supply roll sensor 50 as a single sensor, it is also understood that the more than one signal representative of the wrap distance (WD) 52 can be communicated to the controller 80 by more than one supply roll sensor 50.

The at least one supply roll sensor 50 can be, although is not limited to, one of an optical sensor, a sonic sensor, or a magnetic field sensor. A non-limiting example of an optical sensor is the Wenglor Photoelectronic Sensor part number OCP662X0080. A non-limiting example of a sonic sensor is the Wenglor Ultra Sonic detector part number UMF402U035.

The system 10 can also include a core sensor 60 that is positioned relative to the roller 12 to sense a core distance (CD) 62 between the core sensor 60 and the core outside face 34. Preferably, the position of the core sensor 60 can be a second radial distance (2RD) 64 from the longitudinal axis 14, so that the core sensor 60 is not in physical contact with the supply roll 20. The second radial distance (2RD) 64 may be the same or different than the first radial distance (1RD) 54.

The core sensor 60 can communicate with the controller 80. Communication with the controller 80 can be, but is not limited to, electrical signal, optical signal, sonic signal, electromagnetic signal, any other wireless signal processes, induction, or user input of data read from the core sensor 60. The core sensor 60 can communicate one or more signals representative of the sensed core distance (CD) 62 to the controller 80, which can, among other things, analyze the signal(s) to identify possible outliers; or determine an average value related to the signal(s) to determine the best approximation of the core distance (CD) 62. Further, while FIG. 1A, FIG. 1C, FIG. 2, and FIG. 3 demonstrate the core sensor 60 as a single sensor, it is also understood that the more than one signal representative of the core distance (CD) 62 can be communicated to the controller 80 by more than one core sensor 60.

The core sensor 60 can be, although is not limited to, one of an optical sensor, a sonic sensor, or a magnetic field sensor. A non-limiting example of an optical sensor is the Wenglor Photoelectronic Sensor part number OCP662X0080. A non-limiting example of a sonic sensor is the Wenglor Ultra Sonic detector part number UMF402U035. Additionally or alternatively, the core sensor 60 can communicate information from the information label 22 to the controller 80. A non-limiting example of a communicating scanner is the Wenglor Barcode Reader part number FIS-0003-0103.

The system 10 can also include a rotation sensor 70 that is positioned relative to the roller 12 to sense a number of rotations of the core 30. The rotation sensor 70 may be positioned a third radial distance (3RD) 72 from the longitudinal axis 14, or it may be positioned in any other location consistent with well-known techniques to sense a number of rotations of the supply roll 20.

The rotation sensor 70 can communicate with the controller 80. Communication with the controller 80 can be, but is not limited to, electrical signal, optical signal, sonic signal, electromagnetic signal, any other wireless signal processes, induction, or user input of data read from the rotation sensor 70. The rotation sensor 70 can communicate one or more signals representative of the number of core rotations to the controller 80, which can, among other things, analyze the signal(s) to identify possible outliers; or determine an average value related to the signal(s) to determine a best approximation of the number of core rotations. Further, while FIG. 1A, FIG. 1C, FIG. 2, and FIG. 3 demonstrate the rotation sensor 70 as a single sensor, it is also understood that the more than one signal representative of the number of core rotations can be communicated to the controller 80 by more than one rotation sensor.

The rotation sensor 70 can be, although is not limited to, one of an optical sensor, a sonic sensor, an encoder, a barcode scanner, or a magnetic field sensor. A non-limiting example of an optical sensor is the Wenglor Photoelectronic Sensor part number OCP662X0080. A non-limiting example of a sonic sensor is the Wenglor Ultra Sonic detector part number UMF402U035. A non-limiting example of a barcode scanner is the Wenglor Barcode Reader part number FIS-0003-0103. Additionally or alternatively, the rotation sensor 70 can communicate information from the information label 22 to the controller 80.

The system 10 can further include a user interface 28 that can communicate with the controller 80. Communication with the controller 80 can be, but is not limited to, electrical signal, optical signal, sonic signal, electromagnetic signal, any other wireless signal processes, induction, or user input. Non-limiting examples of the user interface 28 can include one or more of: a mobile device, a touch screen, a keyboard, a monitor, a light emitting diode or other light source, a speaker, or a microphone. Examples of information that can be communicated to the controller 80 via the user interface 28 can include, but are not limited to: the thickness of the wound stretch film 40; a length of the wound stretch film 40; the wrap distance (WD) 52; a core radius including: the core inside radius (CIR) 36 and/or the core outside radius (COR) 38; the core distance (CD) 62; one or more dimensions of the core 30; the length of the core 30; one or more dimensions of the wound stretch film 40; one or more elastic properties of the wound stretch film 40; one or more chemical properties of the wound stretch film 40; one or more manufacturing properties of the supply roll 20; the number of rotations of the core 30; and/or a programmed sequence of steps for operation of the system, such a start and stop times, sensor sampling rates, acceptable tolerances in measure, etc. Additionally or alternatively, the user interface 28 can be used to communicate data to a user. Non-limiting examples of data that can be communicated to the user via the user interface 28 include: the amount of stretch film unwound from the supply roll 20; an indication to change the supply roll 20; the thickness of the wound stretch film 40; a length of the wound stretch film 40; the wrap distance (WD) 52; the core outside radius (COR) 38; the core inside radius (CIR) 36; the core distance (CD) 62; one or more dimensions of the core 30; the length of the core 30; one or more dimensions of the wound stretch film 40; one or more elastic properties of the wound stretch film 40; one or more chemical properties of the wound stretch film 40; or one or more manufacturing properties of the supply roll 20; or the number of rotations of the core 30.

FIG. 3 schematically illustrates the controller 80 that can be provided with a memory 82 and a central processing unit (CPU) 84. The memory 82 can be used for storing control software that can be executed by the CPU 84 that among other things, is configured to calculate amounts based on measurement signals, operate a stretch film wrapping cycle, and to perform a variety of other functions. The memory 82 can also be used to store information, such as, but not limited to, a look up table or a database. The look up table or the database can be used to store data received from one or more components of the system 10 that can be communicably coupled with the controller 80. The look up table or database can be used to store the various operating parameters for the one or more cycles of operation, including factory default values for the operating parameters and any adjustments to them by sensed measurements or by user input.

The controller 80 can be operably coupled with one or more components of the system 10 for communicating with and/or controlling the operation of the components to sense a measurement or participate in a stretch film wrapping cycle. The controller 80 can communicate with the at least one supply roll sensor 50 to receive one or more signals representative of the wrap distance (WD) 52. Optionally, the controller 80 can control the at least one supply roll sensor 50. The controller 80 can, but is not limited to, activating the at least one supply roll sensor 50 and/or establishing a sampling rate at which is the at least one supply roll sensor 50 communicates a signal representative of the wrap distance (WD) 52 to the controller 80.

Additionally, the controller 80 can communicate with the core sensor 60 and/or the rotation sensor 70 to receive one or more signals representative of the core distance (CD) 62 and/or the number of core rotations, respectively. Optionally, the controller 80 can control the core sensor 60 and/or the rotation sensor 70. The controller 80 can, but is not limited to, activating the core sensor 60 and/or the rotation sensor 70 and/or establishing a sampling rate at which the core sensor 60 and/or the rotation sensor 70 communicates a signal representative of the core distance (CD) 62 and/or the number of core rotations, respectively, to the controller 80.

The controller 80 can couple to the user interface 28 for receiving user selected inputs and communicating information to the user. The controller 80 can also communicate with and/or control various additional sensors 86, which are known in the art and not shown for simplicity. Optionally, the controller 80 can couple to local or remote servers 88 to obtain or communicate data. Non-limiting examples of data communicated to or obtained from a local or remote server 88 include: the amount of stretch film unwound from a supply roll 20 during a wrapping cycle; the length of the wound stretch film 40 on the supply roll 20; the thickness of the wound stretch film 40; an indication to change the supply roll 20; the wrap distance (WD) 52; the core outside radius (COR) 38; the core inside radius (CIR) 36; the core distance (CD) 62; one or more dimensions of the core 30; the length of the core 30; one or more dimensions of the wound stretch film 40; one or more elastic properties of the wound stretch film 40; one or more chemical properties of the wound stretch film 40; or one or more manufacturing properties of the supply roll 20; or the number of rotations of the core 30.

FIG. 4 illustrates a method 200 of measuring an amount (L) of wound stretch film 40 that is unwound from the core 30 of the supply roll 20 about a longitudinal axis 14. While the method 200 shown in FIG. 4 is discussed in the context of the embodiment of the system 10 and the supply roll 20 shown in FIG. 1A, FIG. 1B, FIG. 1C, FIG. 2, and FIG. 3, it is also understood that the method can be employed with other embodiments of the system 10 and the supply roll 20.

In step 201, the method 200 starts before an amount (L) of wound stretch film 40 is unwound from the core 30 of the supply roll 20. In step 202, a first distance (WD_(first)) is measured. The first distance (WD_(first)) can be measured from at least one point radially away from the supply roll 20 to the stretch film outside face 44 of the supply roll 20. The first distance (WD_(first)), preferably, is measured before an amount (L) of wound stretch film 40 is unwound from the core 30 of the supply roll 20. The first distance (WD_(first)) can be measured by the at least one supply roll sensor 50 and a signal representative of the first distance (WD_(first)) can be communicated to the controller 80.

Step 203 can occur as an alternative to step 202 or in addition to step 202. In step 203, a second distance (WD_(second)) is measured. The second distance (WD_(second)) can be measured from at least one point radially away from the supply roll 20 to the stretch film outside face 44 of the supply roll 20. The second distance (WD_(second)), preferably, is measured when an amount (L) of wound stretch film 40 has been unwound from the core 30 of the supply roll 20. The second distance (WD_(second)) can be measured by the at least one supply roll sensor 50 and a signal representative of second distance (WD_(second)) can be communicated to the controller 80.

A third distance is obtained in step 204. The third distance can be measured from at least one point radially away from the supply roll 20 to the core outside face 44 of the supply roll 20. The third distance can be obtained after step 201 and before step 205. Therefore, step 204 can occur before, during, or after step 202 and/or step 203.

In step 205, the amount (L) of wound stretch film 40 that is unwound from the core 30 of the supply roll 20 can be determined. Non-limiting examples of alternative or additional dimensions that can be utilized for determining the amount of stretch film unwound from the supply roll include: the thickness of the wound stretch film 40, the roller radius (RR) 16, the core outside radius (COR) 38, the core inside radius (CIR) 36, the first radial distance (1RD) 54, the second radial distance (2RD) 64, or the third radial distance (3RD) 72. Examples of how the alternative or additional dimensions can be obtained include, but are not limited to, one or more of the at least one supply roll sensor 50, the core sensor 60, the rotation sensor 70, the information label 22, the additional sensors 86, the local or remote servers 88, the memory 82, calipers, or user input. A signal, representative of the alternative or additional dimension can be communicated with or recalled by the controller 80.

One exemplary calculation for determining the amount (L) of wound stretch film 40 unwound from the core 30 of the supply roll 20 (L) is given in Equation (1) below:

L=πn(2R+d(n+1))  (1)

where L refers to the amount of wound stretch film 40 unwound from a supply roll 20, n refers to the number of rotations of the core 30, R refers to the stretch film outside radius (SFOR) 47 after the amount (L) of stretch film has been unwound, and d refers to the thickness of the wound stretch film 40.

An exemplary calculation for determining the stretch film outside radius (SFOR) 47 after amount L of stretch film has been unwound (R) can be shown in Equation (2):

R=(COR)+(CD−WD_(second))  (2)

where COR refers to the core outside radius (COR) 38 which can be a known additional dimension or calculated using the third distance. The third distance measured in step 204 is the core distance (CD) 62 that can be measured by the core sensor 60. WD_(second) refers to the second distance that can be measured in step 203. Non-limiting examples of how the core outside radius (COR) 38 can be known include: the information label 22, a look-up table, a direct measurement, previously stored information, or any other methods or resources known in the art. A non-limiting example of how the core outside radius (COR) 38 can be calculated using the core distance (CD) 62 includes subtracting the core distance (CD) 62 from a known distance such as, but not limited to, the second radial distance (2RD) 64.

Other non-limiting examples of calculations for determining the stretch film outside radius (SFOR) 47 after amount L of stretch film has been unwound (R) are given in Equation (3) and Equation (4) below:

R=(1RD−WD_(second))  (3)

where 1RD refers to the first radial distance (1RD) 54 which can be a known additional dimension or calculated using measurements from steps 202 or 204. Non-limiting examples of how the first radial distance (1RD) 54 can be known include: a barcode, a look-up table, a direct measurement, previously stored information, or any other methods or resources known in the art. WD_(second) refers to the second distance measured in step 203.

R=(COR)+(CD−(WD_(first) +dn))  (4)

where COR refers to the core outside radius (COR) 38 which can be a known additional dimension or calculated from the third distance as demonstrated in the present disclosure. The third distance measured in step 204 is the core distance (CD) 62 that can be measured by the core sensor 60. WD_(first) refers to the first distance measured in step 202, d refers to the thickness of the wound stretch film 40 and n refers to the number of rotations of the core 30, where d and n are additional dimension known or calculated using measurements from steps 202, 203 or 204. Non-limiting examples of how d and n can be known include: the information label 22, a look-up table, a direct measurement, previously stored information, or any other methods or resources known in the art.

The number of core rotations (n) can be calculated using an exemplary equation (5):

$\begin{matrix} {n = \left( \frac{{WD_{second}} - {WD_{first}}}{d} \right)} & (5) \end{matrix}$

where WD_(first) refers to the first distance measured in step 202, WD_(second) refers to the second distance measured in step 203, and d refers to the thickness of the wound stretch film 40, where d is an additional dimension that is known or calculated using measurements from steps 202, 203 or 204. Examples of how d can be known include: the information label 22, a look-up table, a direct measurement, previously stored information, or any other methods or resources known in the art.

Optionally, in step 207, the number of core rotations (n) can be sensed using the core sensor 60 or the rotation sensor 70.

The thickness of the wound stretch film 40 (d) can obtained from the information label 22 and sensed by the core sensor 60 or the rotation sensor 70, or a look-up table, or a direct measurement, or previously stored information, or any other methods or resources known in the art. Alternatively, the thickness of the wound stretch film 40 (d) can be calculated using the exemplary equation (6):

$\begin{matrix} {d = \left( \frac{{WD_{second}} - {WD_{first}}}{n} \right)} & (6) \end{matrix}$

where WD_(first) refers to the first distance measured in step 202, WD_(second) refers to the second distance measured in step 203, and n refers to the number of rotations of the core 30, where n is an additional dimension sensed in step 207 or calculated using measurements from steps 202, 203 or 204 as demonstrated in the present disclosure.

The method 200 ends in step 206 after the amount (L) of wound stretch film 40 is unwound from the core 30 of the supply roll 20 and that amount (L) has been determined.

Optionally, before the method 200 ends in step 206, step 208 can provide an indication when the determined amount of stretch film unwound from the supply roll 20 is at a predetermined threshold. The indication that a predetermined threshold has been reached can be communicated to the user via the user interface 28 or other methods known in the art.

The measuring steps 202, 203 and the determining step 205 of the amount (L) of stretch film unwound from the supply roll can be done contemporaneously. The method 200 can start prior to a wrap cycle and end once the wrap cycle is complete and the amount (L) of stretch film unwound is determined. Additionally or alternatively, the method 200 can run during the wrap cycle so that between any two moments in a wrap cycle or throughout the wrap cycle, the amount (L) of wound stretch film 40 that has been unwound from the core 30 can be determined 205.

To the extent not already described, the different features and structures of the present disclosure can be used in combination with each other as desired. For example, one or more of the sensors illustrated and/or described with respect to the system 10 can be used to sense one or more of the measurements discussed herein. Additionally, one or more sensors can be combined with other sensors or features to obtain one or more of the measurements discussed herein to calculate an amount of stretch film unwound from the supply roll 20. That one feature may not be illustrated in all the embodiments and is not meant to be construed that it cannot be, but is done for brevity of description. Thus, the various features of the different embodiments can be mixed and matched as desired to form new embodiments, whether or not the new embodiments are expressly described.

Equations are not limited to radial measurements. Any diameter measurement can easily be processed or calculated to a radius; likewise a radial measurement can easily be converted to a diameter. The equations given as examples in the present disclosure are not limiting and a variety of sensed data can be combined using different algorithms to find the amount of stretch film unwound from a supply roll.

While aspects of the present disclosure have been specifically described in connection with certain specific embodiments thereof, it is to be understood that this is by way of illustration and not of limitation. Reasonable variation and modification are possible within the scope of the forgoing disclosure and drawings without departing from the spirit of the present disclosure which is defined in the appended claims. 

What is claimed is:
 1. A system for determining an amount of stretch film unwound from a stretch film dispensing apparatus wherein stretch film is unwound from a supply role on a roller that rotates on a longitudinal axis, the system comprising: at least one supply roll sensor positioned relative to a roller in the stretch film dispensing apparatus to sense a distance from the at least one supply roll sensor to an outside face of a supply roll on a core on the roller; a controller connected to the at least one supply roll sensor; and a core sensor positioned relative to the roller to sense a core distance from the core sensor to an outside face of the core and configured to send a signal representative of the core distance to the controller; wherein the at least one supply roll sensor is configured to take a first measure of the distance and, after stretch film is unwound from the supply roll, take a second measure of the distance, and send signals representative of the first and second measures of the distance to the controller; and wherein the controller is configured to determine the amount of stretch film unwound based on signals representative of at least one of the first or second measure, and the core distance.
 2. The system of claim 1, wherein the at least one supply roll sensor is one of an optical sensor or a sonic sensor.
 3. The system of claim 1, wherein the core sensor is one of an optical sensor or a sonic sensor.
 4. The system of claim 1, further comprising a rotation sensor positioned to sense a number of rotations of the core, and send a signal representative of the number of rotations to the controller, and the controller is configured to determine the amount of stretch film unwound based also on the number of rotations.
 5. The system of claim 4, wherein the rotation sensor is one of an optical sensor or a sonic sensor.
 6. The system of claim 1, wherein the controller is configured to obtain data about a thickness of the stretch film on the supply roll and the controller is configured to determine the amount of stretch film unwound based also on the data.
 7. The system of claim 6, wherein the controller is configured to obtain the data from one of a remote server, a local server, an input, a barcode on the stretch film, an image or graphic on the stretch film, a barcode on the supply roll packaging, a barcode on the core, a look-up table, or a color or numeric indicator.
 8. The system of claim 1, wherein the at least one supply roll sensor is positioned to sense the distance from a lower portion of the outside face of the supply roll.
 9. The system of claim 1, further comprising an indicator coupled to the controller to provide an indication of the amount of stretch film unwound.
 10. A method of measuring an amount of stretch film unwound from a core of a supply roll about a longitudinal axis, the method comprising: measuring at least one of a first distance from at least one point radially away from the supply roll to an outside face of the supply roll or a second distance from the at least one point radially away from the supply roll to the outside face of the supply roll after stretch film has been unwound from the supply roll; measuring at a third distance from at least one point radially away from the supply roll to an outside face of the core; and determining an amount of stretch film unwound from the supply roll based on the at least one of the first and second distances, and the third distance.
 11. The method of claim 10, further comprising sensing a number of rotations of the core and determining an amount of stretch film unwound from the supply roll based also on the number of rotations.
 12. The method of claim 10, further comprising indicating when the determined amount of stretch film unwound from the supply roll is at a predetermined threshold.
 13. The method of claim 10, wherein the measuring is done with one of an optical sensor or sonic sensor.
 14. The method of claim 10, wherein the determining is based also on a thickness of the stretch film on the supply roll.
 15. The method of claim 10, wherein the measuring and the determining of the amount of stretch film unwound from the supply roll is done contemporaneously.
 16. The method of claim 10, wherein the measuring comprises measuring the first distance and the second distance, and the determining of the amount of stretch film unwound from the supply roll is based on the first distance, the second distance, and the core distance. 